'Snowmaggedon'? Nope. Not Even 'Snowpocalypse'

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Just in time for winter, new analysis shows that even though
headlines in the last two winters might make you think we had
intensely cold seasons, the truth is just the opposite.

In fact, there were actually more especially warm than especially
cold winter days both seasons, new analysis shows.

"In the last couple of winters, there has been an inordinate
amount of coverage of cold conditions in many places, and also
questions about what these cold extremes mean for climate
change," said Alexander Gershunov of Scripps Institution of
Oceanography at the University of California, San Diego. His team
wanted to look at whether the actual temperatures backed up all
of these news reports.

"We focused on the last two winters that were notoriously cold in
certain places, especially parts of Europe and Siberia and the
eastern, especially southeastern, US," Gershunov said.

The team examined temperature records throughout the northern
hemisphere going back to 1948 and compared the coldest and
warmest five percent of days in each of the last two winters with
the long-term trends.

"The strongest extremes of the last two winters were actually not
cold, they were warm," he said. "The warm extremes in many places
were unprecedented. They were much more widespread, and covered a
lot more of the northern hemisphere than the cold extremes did."

While the cold extremes for the northern hemisphere for the
2009-2010 and 2010-2011 winters ranked 21st and 34th,
respectively, the warm extremes ranked 12th and fourth, according
to the findings, which will appear in Geophysical Research
Letters.

"The cold extremes were prominent, but they were not
unprecedented," Gershunov said.

The researchers also found that the cold weather could be
explained by the North Atlantic Oscillation, a natural climate
cycle like El Niño which produces cycles of warmer or colder
weather in North America and Europe. Indeed, were it not for
ongoing climate warming, the oscillation would have generated
even colder temperatures, Gershunov said.

In contrast, these climate cycles did not explain the anomalously
warm days. "The warm extremes were only consistent with a
long-term warming trend, which we can also see very clearly on
this record," Gershunov said.

Climate swings occur over many timescales, agreed Anastasios
Tsonis of the University of Wisconsin, Milwaukee, including those
created by the oscillations. "These swings are natural," he said.
"The overall warming has not stopped."

Heavy snows such as "Snowmageddon" or "Snowpocalypse" which hit
the eastern US and Canada captured news attention. But these also
reflect no reprieve from climate change. "It's wrong to equate
snow with extreme cold," Gershunov said. "It never snows when
it's really cold."

"I think what our results clearly show is how natural climate
variability and regional extremes should not be confused with
long-term trends that involve the entire globe," he said.